Mechanical drive



March 28, 1939. F, KQEPFLE 2,152,550

MECHANICAL DRIVE Filed June 17, 1937 Fig.1.

Fig.3. ,2

III/II I/IIA :JWUQAVM c/O SEPH F'. KOEP Patented Mar. 28, 1939 UNITED STATES PATENT OFFICE MECHANICAL DRIVE Application June 17, 1937, Serial No. 148,811

7 Claims.

This invention relates to improvements in electro-mechanical cranking devices or starters for gasoline and oil combustion engines, automotive and stationary.

The objects of the invention are to eliminate the undesirable features and mechanical defects of conventional engine-starters, such as: excessive vibration of the starter mechanism; breaking of gear teeth; and damage to the motor housing: also to prevent bending of the starter motor shaft by reducing to a minimum the strain of the driving torque.

An additional object of the invention is to provide a starter mechanism of such construction and design that the driving torque incident to the starting action is taken on the starter shaft close to the starter motor and under the bushing supporting the starter pinion.

Other objects and advantages of the invention will become apparent from the following detailed description thereof read in connection with the accompanying drawing, wherein:

Figure 1 is a View of a starter motor shaft with the starter pinion and its associated parts shown in section.

Figure 2 is a cross section on line 2-2 of Figure 1, and

Figure 3 is a cross section on line 33 of Figure 1.

The motor of the electrical starter mechanism is represented in dotted lines at Ill and a portion of the armature shaft is shown at I I. The armature shaft has a reduced extension I2 which in the drawing is shown broken off at the outer 5 end I3. In actual practice, however, the extension shaft I2 is so constructed that either terminal may be used as the driving end. In other words, the starter shaft maybe used on either the right or left side of the starter motor which may be used as a stop at either end of the shaft. The shaft I2 carries a threaded sleeve or bushing I4 which is secured to the shaft by a straight spline l5 so as to rotate with the shaft and at the same 1 time be free to slide longitudinally of the shaft. Mounted on the bushing is the starter pinion I6 which has a counterweight II, fastened thereto. This starter pinion has internal threads I8 meshing with the threads I9 of the bushing. As a feature of the invention, a very short bushing with a triple cut thread is employed to reduce the distance necessary to be traveled by the starter pinion for coming into mesh with the fly wheel gear, a section of which is shown at 20, and, to cause the pinion to be advanced quickly into full mesh with the fly wheel gear and against the stop 2I which limits the forward movement of the starter pinion.

The threaded bushing is arranged to float in the longitudinal direction of the starter shaft between compression springs 22 and 23. Spring 22 encir- 5 cles the starter shaft I2 between the forward end of the bushing and the adjacent side of the starter motor; one end of the spring having a bearing on a ring 24 pressed on the shaft close to, but spaced slightly from the motor and the other 10 end of the spring having a bearing against the stop 2|. Spring 23 encircles the starter shaft at the opposite end of the bmhing; the outer end of the spring having a bearing against an adjustable assembly set collar 25 held tight to the 15 shaft by a headless bolt 26, as shown in Figure 2, and the inner end of the spring having a bearing against a friction ring 21. The rings 2I and 27 are slidable on the starter shaft and are held against the ends of the bushing by the force of 25 the compressed springs 22 and 23, the relative strength of which is so proportioned that in the inactive condition of the starter the normal or neutral positions of the bushing and the starter pinion are as illustrated in Figure 1. The bush- 25 ing is a straight length of tubing requiring nothing fastened to its ends to keep it balanced while floating in driving position. The starter pinion is inter-changeable to right or left so that the drive can be used on the right or left side of the 30 motor.

When the starting motor is set in operation, the threaded bushing I4 turns with the shaft I2 and the starter pinion I6, being held from turning by reason of its inertia and the weight I1, 35 advances on the threads of the bushing in the direction of the non-rotating fly wheel gear 20. Due to the action of the trip-1e cut thread the advance of the starter pinion toward the fly wheel gear is very rapid and when the pinion meets an 40 obstruction, as when the teeth of the fly wheel gear and the starter pinion come into abutment endwise, the pinion and the bushing rebound in the direction of the spring 23 which yields to permit the bushing to shift to the right in Figure 1 to bring the starter pinion back to its original or neutral position and at the same time it acts as a shock absorber to cushion the rebound. But when the pinion meets no obstruction and meshes with gear 20 when it is moved forward, or to the 0:

left in Figure 1, the action of the bushing places the pinion in full mesh and any rebound or forward movement or momentum occasioned by the reaction of the spring 23 is cushioned by the stop 2I and the spring 22. When the starter pinion 55 I6, while in mesh with the fly wheel gear 20, is unable to advance farther on the screw bushing M by reason of its abutment with the stop 2| and the resistance of the cushion spring 22, the bushing slides back on the shaft l2 or to the right in Figure 1 and further compresses the spring 23; the starter pinion l6 being prevented from turning by its meshing with the stationary fly wheel gear 20. This retrograde movement of the bushing continues until the spring 23 is compressed to a degree suflicient to supply the force necessary to turn the engine over.

After the engine fires, the starter pinion is rotated by the fly wheel gear in the same direction as the rotating starter motor shaft but at a speed in excess of the latter, as a result of which, and the action of the triple cut thread it is thrown back on the threaded bushing M to and against the friction ring 21 while at the same time the spring 23 thrusts the bushing in the opposite direction until the pinion and the bushing are returned to their original or neutral position. The rotating pinion l6 upon coming into contact with the spring-pressed friction ring 2! is brought to rest, the pressure exerted by the ring 2'! and the spring 23 against the starter pinion l6 binding the latter against the screw threads of the bushing without interfering with the forward movement of the pinion in the starting operation.

By reason of the cushion springs at the opposite ends of the floating bushing, the strains and stresses set up when the bushing comes to a sudden stop are absorbed and dissipated and a smoother starting action is obtained with minimum clashing of gears and maximum avoidance of breakage of springs or gear teeth. The cushioning means between the starter motor and the adjacent end of the threaded bushing holds the bushing and the starter pinion from any destructive impact with the motor. Because of the location of the spline IS, the driving torque is directly on the shaft l2 close to the starter motor In and under the bushing M. The strain'of the driving torque is thereby reduced to a minimum and the bending or other distortion of the starter motor shaft is prevented.

Having thus described the invention I claim:

1. A starter drive including a starter shaft, a threaded sleeve rotatable with and solely axially slidable on theshaft, a weighted starter'pinion threaded on said sleeve, and cushioning means bearing on each end of the sleeve for resisting the sliding movement of the latter in both directions.

2. A starter mechanism including a starter shaft, a short sleeve rotatable with and solely axially slidab-le on the said shaft and having an external multi-cut thread, a weighted starter pinion threaded on the said sleeve, and cushioning means bearing on each end of the bushing and lying in the path of the pinion for resisting the sliding movements of the pinion'with respect to the bushing and the bushing with respect to the shaft.

3. In a starter mechanism, a starter motor, a starter motor shaft, a threaded sleeve having a straight spline connection with said shaft close to the motor to be rotated with the shaft and free to slide axially thereon, a weighted starter pinion threaded directly to said sleeve for movement into mesh with a flywheel gear, and cushioned stops at opposite ends of the sleeve and floatingly supporting the latter under resistance to endwise movement in. opposite directions from a neutral position beyond the side of the flywheel gear which is remote from the starter motor.

4. In a starter mechanism, a starter motor, a

starter motor shaft, a threaded sleeve having a straight spline connection with said shaft close to the motor to be rotated with the shaft and free to slide axially thereon, a weighted starter pinion threaded directly to said sleeve for movement into mesh with a flywheel gear, and cushioned stops at opposite ends of the sleeve and floatingly supporting the latter under resistance toendwise movement in opposite directions from a neutral position beyond the side of the flywheel gear which is remote from the starter motor, said stops including spring-backed rings.

5. A starter mechanism comprising a drive shaft, an externally threaded sleeve slidably connected with the shaft by a straight spline so as to rotate uniformly with the shaft, said sleeve being of a unitary construction to cause a uniform tary force transmitted by the sleeve, and means mounted on the shaft to support the sleeve in a neutral position under tension opposing the sliding movement of the sleeve in both directions.

6. A starter mechanism comprising a drive shaft, an externally threaded sleeve slidably connected with the shaft by a straight spline so as to rotate uniformly with the shaft, said sleeve'being of a unitary construction to cause a uniform transmission of rotary force throughout the en tire area thereof, a weighted starter pinion threaded on the sleeve to receive the uniform rotary force transmitted by the sleeve, and springs mounted on the shaft and bearing on each end of the sleeve to exert resistance to the sliding movement of the sleeve in both directions.

7. A starter mechanism comprising a starter motor, a shaft driven by said motor, a sleeve slidably connected with the shaft by a straight spline so as to rotate uniformly with the shaft, said sleeve having an external cut thread, said sleeve also being of a unitary construction to cause a uniform transmission of rotary force throughout the entire area thereof, a weighted starter pinion threaded on the sleeve to receive the uniform rotary force transmitted by the sleeve, a compression spring embracing the shaft in compressed condition between the motor and the adjacent end of the sleeve, a stop ring mounted loosely on the shaft and bearing on one end of the spring (and also bearing on said adjacent end of the JOSEPH F. KOEPFLE. 

